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From: Yinghai Lu <yinghai@kernel.org>
To: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org, Stoney Wang <song-bo.wang@hp.com>,
	Yinghai Lu <yinghai@kernel.org>,
	stable@kernel.org
Subject: [PATCH v4] x86, apic: Check fadt x2apic phys in x2apic_phys_probe()
Date: Thu,  7 Feb 2013 10:53:02 -0800
Message-ID: <1360263182-16226-1-git-send-email-yinghai@kernel.org> (raw)
In-Reply-To: <CAE9FiQVT7Q1=NOcTvzkmskQLpfvuX+JSW_9NBXjx7z77TDHz3Q@mail.gmail.com>

From: Stoney Wang <song-bo.wang@hp.com>

When a HP ProLiant DL980 G7 Server boots a regular kernel,
there will be intermittent lost interrupts which could
result in a hang or (in extreme cases) data loss.

The reason is that this system only supports x2apic physical
mode, while the kernel boots with a logical-cluster default
setting.

This bug can be worked around by specifying "x2apic_phys" or
"nox2apic" boot option, but we want to handle this system without
requiring manual workarounds.

BIOS set ACPI_FADT_APIC_PHYSICAL in FADT table.
As all apicids are less than 255, BIOS need to pass the control
to the OS with xapic mode, according to x2apic-spec, chapter 2.9.

Current code handle x2apic when BIOS pass with xapic mode:
When user specify x2apic_phys, or FADT indicates PHYSICAL.
1. During madt oem check, apic driver is set with xapic logical or
   xapic phys driver at first.
2. enable_IR_x2apic() will enable x2apic_mode.
3. if user specify x2apic_phys, x2apic_phys_probe() will install
   right x2apic phys driver and use x2apic phys mode.
   otherwise will skip and let x2apic_cluster_probe to take over
   to install x2apic cluster driver (wrong one) even FADT indicates
   PHYSICAL, because x2apic_phys_probe does not check FADT PHYSICAL.

Add checking x2apic_fadt_phys in x2apic_phys_probe() to fix the problem.

-v3: update the change according to Ingo.
-v4: merge changelog from Ingo.

[ changelog, and simplify code - Yinghai Lu ]
Signed-off-by: Stoney Wang <song-bo.wang@hp.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: stable@kernel.org

---
 arch/x86/kernel/apic/x2apic_phys.c |   21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

Index: linux-2.6/arch/x86/kernel/apic/x2apic_phys.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/x2apic_phys.c
+++ linux-2.6/arch/x86/kernel/apic/x2apic_phys.c
@@ -20,18 +20,19 @@ static int set_x2apic_phys_mode(char *ar
 }
 early_param("x2apic_phys", set_x2apic_phys_mode);
 
-static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
+static bool x2apic_fadt_phys(void)
 {
-	if (x2apic_phys)
-		return x2apic_enabled();
-	else if ((acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID) &&
-		(acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL) &&
-		x2apic_enabled()) {
+	if ((acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID) &&
+		(acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL)) {
 		printk(KERN_DEBUG "System requires x2apic physical mode\n");
-		return 1;
+		return true;
 	}
-	else
-		return 0;
+	return false;
+}
+
+static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
+{
+	return x2apic_enabled() && (x2apic_phys || x2apic_fadt_phys());
 }
 
 static void
@@ -82,7 +83,7 @@ static void init_x2apic_ldr(void)
 
 static int x2apic_phys_probe(void)
 {
-	if (x2apic_mode && x2apic_phys)
+	if (x2apic_mode && (x2apic_phys || x2apic_fadt_phys()))
 		return 1;
 
 	return apic == &apic_x2apic_phys;

  reply index

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-01-15  1:50 [PATCH] x86/apic: check FADT settings after enable x2apic Stoney Wang
2013-01-28  5:05 ` Wang, Song-Bo (Stoney)
2013-01-28  6:57   ` Yinghai Lu
2013-01-28 10:11     ` Ingo Molnar
2013-01-28 18:10       ` Yinghai Lu
2013-01-29  7:47         ` Ingo Molnar
2013-01-29  8:43           ` Wang, Song-Bo (Stoney)
2013-01-29  8:49             ` Ingo Molnar
2013-01-29 21:30               ` Yinghai Lu
2013-01-29 21:52               ` Yinghai Lu
2013-01-31 11:32                 ` Ingo Molnar
2013-01-31 15:56                   ` Yinghai Lu
2013-02-04  6:41                   ` Wang, Song-Bo (Stoney)
2013-02-04 11:03                     ` Ingo Molnar
2013-02-04 20:29                       ` [PATCH] x86, apic: Check fadt x2apic phys in x2apic_phys_probe() Yinghai Lu
2013-02-05 12:24                         ` Ingo Molnar
2013-02-05 16:53                           ` Yinghai Lu
2013-02-06 13:16                             ` Ingo Molnar
2013-02-06 17:10                               ` Yinghai Lu
2013-02-07 18:53                                 ` Yinghai Lu [this message]
2013-02-11 12:37                                   ` [tip:x86/urgent] x86/apic: Work around boot failure on HP ProLiant DL980 G7 Server systems tip-bot for Stoney Wang
2013-02-18  8:52                                   ` [PATCH v4] x86, apic: Check fadt x2apic phys in x2apic_phys_probe() Lin-Bao Zhang
2013-02-18 17:13                                     ` Yinghai Lu

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